Well all my reasoning was good but for the formula which is actually F = z || (y && x) :-)
Mea culpa I didn't see that the ladder choices are reversed. I let other people try showing that the group is alive in John's initial problem (last move was B capture at x, the lower side ko). --Marcel On 23 June 2018 at 00:06, Marcel Crasmaru <crasma...@gmail.com> wrote: > OK I think there is one thing to be done to make the solution longer: > > 1. mark the middle ko and then > 2. problem should be: B just captured in the middle ko and W is to > move - is the group alive? > > See here: > https://drive.google.com/file/d/1J5Xn4XkOqSsYx0AEBQJj6EL-SjNqNq-o/view?usp=sharing > > Assuming x is the top ko, y the middle one etc. the problem is then > equivalent to > F = z && (y || x) with (x = 1, y = 0, z = 0, F is false) and W cannot play at > y. > > As F is false W has to take the ko at z (x = 1, y = 0, z = 1, F becomes true) > B takes at x (x = 0, y = 0, z = 1 F is false) > W takes at y (x = 0, y = 1, z = 1, F true), > B takes at z (x = 0, y = 1, z = 0, F false) and W is dead as no matter > what W does F remains false (equivalent to ladders failing for W). > > --Marcel > > On 22 June 2018 at 22:27, Marcel Crasmaru <crasma...@gmail.com> wrote: >> Errata: assuming x is the top ko then the formula encoded by this problem is >> >> z && (y || x) >> >> with x = 1, y = 0, z = 0 and W cannot play at z. Thus W is already >> dead you cannot make the formula true. >> >> --Marcel >> >> On 22 June 2018 at 22:19, Marcel Crasmaru <crasma...@gmail.com> wrote: >>> The position looks OK is great - I didn't find any side solutions. >>> Just one observation: I think this encodes x && y || y || z and W is >>> dead already thus is arguably a easier problem :) >>> >>> Should make for a great wall poster. >>> >>> On 22 June 2018 at 19:48, John Tromp <john.tr...@gmail.com> wrote: >>>>>>>> at the bottom of my Go page http://tromp.github.io/go.html, which also >>>>>>>> contains an sgf link. >>>>>>>> Direct link to image: http://tromp.github.io/img/WO5lives.png >>>> >>>> Enlarging the board to 29x29 allows for a much better final (I hope) >>>> look, close to my first attempt. >>>> >>>> -John >>>> _______________________________________________ >>>> Computer-go mailing list >>>> Computer-go@computer-go.org >>>> http://computer-go.org/mailman/listinfo/computer-go _______________________________________________ Computer-go mailing list Computer-go@computer-go.org http://computer-go.org/mailman/listinfo/computer-go
